Corneal epithelial disorders have been posing some problems as symptoms of ophthalmic diseases caused by progression of dry eye or an inappropriate use of contact lenses.
On the other hand, microRNA (miRNA) is a noncoding RNA of 25 nucleotides or so in length that does not contain genetic information, and has a role of binding with messenger RNA (mRNA) within a cell to inhibit the translation to a protein. It has been elucidated that a single kind of miRNA suppresses expression of plural target mRNAs, and that a single kind of mRNA is controlled by plural miRNAs. Further, it has been expected that at least 30% of human genes, or more of gene expressions is controlled by these miRNAs.
In the recent years, a large number of reports have been made on the involvement of miRNA in suppression of cancer or natural immunoreactions, so that the importance of its role is even more remarked. In addition, it has been found that miRNA not only functions in the expressed cells but also is included in membrane vesicles called exosomes to be exported from the cells and transported to other cells through body fluids, so that the translation of mRNA to a protein is also inhibited in the same manner in other cells.
miR-203 is miRNA that is found to be expressed highly in skin, and suggested to be involved in regulation of epidermal differentiation, formation of barrier functions of skin and skin diseases such as psoriasis (Non-Patent Publication 1). miR-203 reportedly has a function as a suppressive factor for cancer or tumors (Non-Patent Publications 2 and 3). In addition, miR-203 reportedly acts to suppress proliferation of vascular smooth muscle cells but not to suppress proliferation of venal epithelial cells of human umbilical chords (Non-Patent Publication 4). However, as far as we know, there are no reports that suggest the associations between corneal epithelial cells and miR-203 at all.